Hi all,
I know a while back that there was some questionable J201's from Tayda. Has anybody purchased any lately and have they worked for you?
Also, has anybody had any experience with their 2N5457's?
Thanks in advance
I've tried 2n5457's from them three times. The first was near the beginning of the year and all of them were fake/out-of-spec. I couple of months ago, I bought four of them to see if there was a difference and they were all good. I recently bought a few of the type they have listed as being from Vishay. I haven't tried or tested these yet, but at least the markings do look right (for being from Siliconix). The set of bad 2n5457's I had were obvious fakes and the printing was wrong on them. They looked as if the faces had been sanded off and then reprinted.
I recently got some 201's and some 5457's from Tayda, and as far as I can tell they work well for me.
Cheers !
Thanks. I think I'll give them another try.
Makes you wonder though, how Mouser says these things are obsolete yet Tayda seems to have a boatload of them. Anybody know how that's happening?
Maybe Mouser treats them as obsolete because no single manufacturer can guarantee a steady supply in the long run while Tayda gets their parts from here and there and doesn't mind switching source often. Just a supposition, though.
Quote from: billstein on October 18, 2013, 10:48:26 PM
Thanks. I think I'll give them another try.
Makes you wonder though, how Mouser says these things are obsolete yet Tayda seems to have a boatload of them. Anybody know how that's happening?
They are obsolete at Mouser because the manufacturer(s) has tagged them as obsolete. In the case of most PTH transistors, the manufacturers have stopped making them altogether at this point. There are still bunches of parts in warehouses though and I'd guess that the majority of those are in Asia.
How many of them are out there though is relative. Mouser is a supplier for electronics manufacturers. So, not being able to get them in the tens of thousands is enough to make them no longer useful for new designs.
Quote from: RobA on October 19, 2013, 12:05:01 AM
Quote from: billstein on October 18, 2013, 10:48:26 PM
Thanks. I think I'll give them another try.
Makes you wonder though, how Mouser says these things are obsolete yet Tayda seems to have a boatload of them. Anybody know how that's happening?
They are obsolete at Mouser because the manufacturer(s) has tagged them as obsolete. In the case of most PTH transistors, the manufacturers have stopped making them altogether at this point. There are still bunches of parts in warehouses though and I'd guess that the majority of those are in Asia.
How many of them are out there though is relative. Mouser is a supplier for electronics manufacturers. So, not being able to get them in the tens of thousands is enough to make them no longer useful for new designs.
Exactly this.
Thanks Rob.
Another question. How do you know when one is good? Is it if the hFe is in range?
As with everything else though, the stuff from the Far East can't be trusted to be legit now...
Two options as far as I'm concerned. Either use SMT (yeah, not a fan of that), or don't use J201s when designing circuits.
Quote from: juansolo on October 19, 2013, 09:58:04 AM
As with everything else though, the stuff from the Far East can't be trusted to be legit now...
Not sure if this statement is universal. Don't western sellers sell exactly the same stuff as most factories are in China anyway?
None of the ones that I use stock them any more as they're OOP. Tayda however, their J201s are fakes now.
Quote from: juansolo on October 19, 2013, 10:11:47 AM
Tayda however, their J201s are fakes now.
Somewhere I have some from a few months ago but I haven't used or tested any. Fakes? Oh my.
Inspired by chromeshere (http://www.madbeanpedals.com/forum/index.php?topic=8802.msg95978#msg95978)'s and marauder (http://www.madbeanpedals.com/forum/index.php?topic=11732.0)'s posts I'd really like to try my hand at SMDs.
Where do you get MMBFJ201s or MMBF5457s in small numbers at reasonable prices?
i got a handful (a thimbleful, really) from Paul's (chromesphere) webshop. if they are out of stock contact him directly, I'm sure he'll hook you up.
Quote from: kothoma on October 19, 2013, 10:05:51 AM
Quote from: juansolo on October 19, 2013, 09:58:04 AM
As with everything else though, the stuff from the Far East can't be trusted to be legit now...
Not sure if this statement is universal. Don't western sellers sell exactly the same stuff as most factories are in China anyway?
It is true that much of this stuff is made in China. Most of the major resellers (in the West or in the East) get parts with known provenance, getting them directly from the manufacturer or from a large distributor. Of course, this generally limits them to current production parts. Places like Mouser and Digikey don't bother with EOL parts.
Many eBay sellers (and I suspect Tayda) get them from smaller component dealers in Asia. These parts can be genuine or not. If something is discontinued (as is the case with through-hole J201 and 2N5457), the chance of fakes increases as there is now motivation for people to relabel other, cheaper components and pass them off as higher price parts.
Now, there are legit places that deal with hard to find parts. But with many of them (particularly on eBay and Alibaba) it is really a roll of the dice. About 6 months ago, I asked one of our consultants to buy some of these two JFets from a dealer in China. It was a distributor with a storefront, not an electronics flea market. They were all fake. I don't know if the distributor knew they were fake or got stuck with them from somebody up the line.
Quote from: kothoma on October 19, 2013, 10:28:36 AM
Where do you get MMBFJ201s or MMBF5457s in small numbers at reasonable prices?
I got me some J201s from Paul's store. Didn't shop around because I wanted to give him some of my business but the price felt reasonable.
Quote from: billstein on October 19, 2013, 07:48:13 AM
Thanks Rob.
Another question. How do you know when one is good? Is it if the hFe is in range?
Sorry, I missed this question earlier. I just build one of the JFET matching circuits on breadboard, usually the one from ROG because it's the easiest to knock together and it works well enough, and measure both the Idss and the cutoff voltage.
Some weird things can happen here though. Like the set of 2n5457's I had that were way out of spec but sounded really good in one of the ROG Fender circuits. The gain from the JFET was pathetic, but this somehow played into the circuit well and actually sounded really good overdrive and distortion wise. I could have designed a nice amp sim around them, but I've only got like 10 or 20 of them and it would have been pointless. I'd really like to know what the JFET's really are, but I can't find anything that actually matches them spec wise. My guess is that they were a set that measured out-of-spec and where scrapped and supposed to be trashed but were lifted from the trash and remarked and sold. They could be anything though. I've even seen reports of BJT's being remarked as JFET's and being sold. That doesn't seem to be the case with these though.
Quote from: RobA on October 28, 2013, 09:00:55 AM
Quote from: billstein on October 19, 2013, 07:48:13 AM
Thanks Rob.
Another question. How do you know when one is good? Is it if the hFe is in range?
Sorry, I missed this question earlier. I just build one of the JFET matching circuits on breadboard, usually the one from ROG because it's the easiest to knock together and it works well enough, and measure both the Idss and the cutoff voltage.
Some weird things can happen here though. Like the set of 2n5457's I had that were way out of spec but sounded really good in one of the ROG Fender circuits. The gain from the JFET was pathetic, but this somehow played into the circuit well and actually sounded really good overdrive and distortion wise. I could have designed a nice amp sim around them, but I've only got like 10 or 20 of them and it would have been pointless. I'd really like to know what the JFET's really are, but I can't find anything that actually matches them spec wise. My guess is that they were a set that measured out-of-spec and where scrapped and supposed to be trashed but were lifted from the trash and remarked and sold. They could be anything though. I've even seen reports of BJT's being remarked as JFET's and being sold. That doesn't seem to be the case with these though.
Thanks. Of course as usual this leads to other questions.
I just put together Jacob's Jfet tester
http://www.madbeanpedals.com/forum/index.php?topic=3098.15
You were talking about two measurements, it looks like this gives one. Would that be the cutoff voltage? Looking at a J201 datasheet it looks like a good component would fall in-between -0.3 and -1.5. Is all this correct.
Thanks everybody for furthering my education in all this.
Yeah, it looks like that tester is measuring the Vgs(off). This works out fine from everything I've seen and measured for JFET matching because the Idss and the Vgs(off) move together. So, if two JFET's match in one parameter, I've always had them match in the other. For the Fetzer valve calcs though, you use both Idss and Vgs(off). For me, I was looking to see if they matched the specified values as well as building some sets to play with in phase shifter circuits.
Those values you have are the same as I've got in the spec sheet for the J201.
Quote from: RobA on October 29, 2013, 05:14:19 PM
Yeah, it looks like that tester is measuring the Vgs(off). This works out fine from everything I've seen and measured for JFET matching because the Idss and the Vgs(off) move together. So, if two JFET's match in one parameter, I've always had them match in the other. For the Fetzer valve calcs though, you use both Idss and Vgs(off). For me, I was looking to see if they matched the specified values as well as building some sets to play with in phase shifter circuits.
Those values you have are the same as I've got in the spec sheet for the J201.
Thank you Rob for being so helpful. :D
You're welcome and I hope you can find some good J201's (for not too much cash). It's a pain that they are getting to be so hard to find now.